Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Qualifying hedges:
Changes in fair value, tax	$ (30)	$ (9)
Reclassification adjustment for amounts included in net income, tax	13	9
Pension and other postretirement benefit plans:
Reclassification adjustment for amounts included in net income, tax	2	0
ALABAMA POWER CO
Qualifying hedges:
Reclassification adjustment for amounts included in net income, tax	0	0
GEORGIA POWER CO
Qualifying hedges:
Changes in fair value, tax	(1)	0
Reclassification adjustment for amounts included in net income, tax	1	0
MISSISSIPPI POWER CO
Qualifying hedges:
Changes in fair value, tax	0	0
Reclassification adjustment for amounts included in net income, tax	0	0
SOUTHERN POWER CO
Qualifying hedges:
Changes in fair value, tax	(21)	(10)
Reclassification adjustment for amounts included in net income, tax	10	8
Pension and other postretirement benefit plans:
Benefit plan net gain (loss), tax	0	0
Reclassification adjustment for amounts included in net income, tax	0	0
SOUTHERN Co GAS
Qualifying hedges:
Changes in fair value, tax	(7)	0
Reclassification adjustment for amounts included in net income, tax	2	0
Pension and other postretirement benefit plans:
Reclassification adjustment for amounts included in net income, tax	$ 1	$ 0

Amount of tax expense (benefit) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580

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Amount, before reclassification, of tax expense (benefit) for gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580

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Amount of tax expense (benefit) for reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

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